The invention concerns a cutting device of an agricultural harvesting machine with several knives arranged alongside each other, that can be repositioned between at least two positions.
DE-A1-197 17 542 discloses a cutting device for an agricultural harvesting machine, for example, a large round baler. This cutting device is equipped with an electronic, optical or mechanical sensor that detects when several knives are not in cutting position and thereby the number of cutting knives has been changed. With this information, the pressure for the repositioning of all knives is controlled in order to assure that they do not offer too great a resistance to deflection upon encountering foreign objects on the one hand, and no inadequately small resistance to deflection for the cutting operation on the other hand.
The problem underlying the invention is seen in the fact that this device can assume that when only a single knife is pivoted that this knife was purposely pivoted in order to change the number of knives able to cut and to increase the retaining pressure on all knives.
According to the present invention, there is provided an improved cutting device for an agricultural machine.
An object of the invention is to provide a cutting device of the type including a plurality of transversely spaced, individually pivoted knives movable between operating and non-operating positions and to provide a sensor for determining if even just one of the set of knives has pivoted from a position occupied by the remaining knives.
A more specific object according to one embodiment is to provide a knife assembly as set forth in the previous object wherein a tie bar arrangement spans all of the knives and is deflected if any one of the knives moves from its working or operating position, this deflecting effecting operation of a sensor. The tie bar may be a wire, a steel cable, a chain, a rod or the like that is strongly tensioned in each case with the sensor being a switch that is operated by nearly every movement of the tie bar. If desired, the switch may be located in circuitry including a time delay element which would prevent the operation of the switch from energizing a warning device when the movement of the knife from its operating position is only transitory, i.e., of short duration.
Another object according to a different embodiment is to provide a variation of the tie bar where it is constructed of first and second sets of electrical conducting segments of an electrical lead with the first and second sets of segments establishing a current path from end to end through the lead when the knives are all in a working position and with the first set of segments respectively being carried by individual knife positioning elements such that an open circuit is established in said lead when any one of the individual knives pivots to a non-working position.
These and other objects of the invention will become apparent from a reading of the ensuing description together with the appended drawings.